The invention relates to an open-end friction spinning machine with a plurality of adjacently arranged spinning positions which each include two adjacently arranged friction rollers driven in the same rotational direction and forming a wedge-shaped gap of which at least one of the friction rollers rotates out of the wedge-shaped gap and exhibits a closed coating or cover surface.
An open-end friction spinning aggregate is described in German Published Unexamined Patent Application (DE-OS) 29 43 063 wherein the rollers rotating out of the wedge-shaped gap exhibit a closed cover or coating surface, while the roller rotating towards or into the wedge-shaped gap includes a perforated coating surface and a suction device within its interior region which is directed towards the wedge-shaped gap. In certain cases, an open end friction spinning machine is constructed from a plurality of such spinning units. The roller displaying a closed cover surface includes a coating or a layering of an elastic material, for example, natural or synthetic caoutchouc (India rubber). By using a roller with a closed cover surface, the structural costs are reduced since in such cases a second suction device becomes unnecessary and especially because the second roller would not need a perforation requiring substantial manufacturing expenditures. Practical tests, however, have shown that with such a device the quality of the yarn experiences substantial fluctuations, whereby a change in quality may result after relatively short or longer periods of time.
The invention is based upon the problem to so design an open-end friction spinning machine of the kind mentioned above so that a yarn of a consistent quality can be obtained.
This problem is solved according to the invention by providing one or several devices for the conditioning of the surfaces of at least those rollers with closed cover surfaces.
The invention is based, at least in part, on the knowledge established through tests that the change of yarn quality is caused by a substantial change in the friction characteristics of the rollers with closed cover surfaces, which surfaces preferably contain a non-metallic layer. Through the device or devices for conditioning the surfaces according to the present invention, constant friction characteristics of the rollers are obtained which then lead to a constant yarn quality.
According to a first preferred embodiment of the invention it is provided that each spinning unit is equipped with a device for conditioning the surfaces of the rollers with closed coating surfaces. These devices are preferably continuously driven so that the friction characteristics remain consistently constant. An electrostatic charge of the roller surfaces is advantageously avoided, for example, by providing the devices with a metallic conductor adjacent to the roller surfaces which is grounded.
In most cases, it is sufficient in practice according to other preferred embodiments of the invention to provide periodic conditioning of the surfaces of the rollers. According to one preferred embodiment it is provided that the roller conditioning devices of these spinning units are jointly operable by means of a central drive. Accordingly, another preferred embodiment is provided wherein the roller conditioning devices of the individual spinning units are selectively switched into operation by means of a maintenance device movable alongside the spinning machine. A central drive is thereby made unnecessary since activating the devices is assumed by the maintenance device which in most cases is already present for other machine maintenance operations.
According to another embodiment of the invention a maintenance device which is movable along the spinning machine is provided, the same being movable to the respective individual spinning units and including a device for conditioning the surfaces of at least the rollers with closed coating surfaces. According to certain preferred arrangements, it is provided that the movable maintenance device passes to the single spinning units in a predetermined time interval. Alternatively or in addition to this arrangement, preferred embodiments are contemplated wherein the movable maintenance device attends to a conditioning of the surfaces during a yarn break, or during a spool exchange, or prior to a start spinning after a machine operational stand still.
In certain embodiments of the invention it is provided that the device for conditioning includes a cleaning device movable to the surfaces of the rollers with closed shell surfaces. In many cases the cleaning alone already results in maintaining constant friction characteristics since thereby also the contaminations are removed which are carried by the supplied fibers, as for example dust, waxes or greases, or the like which will stick to the closed shell or cover surfaces and especially in the pores thereof. Cleaning devices are herewith contemplated having brush-like or scraping elements. It is also contemplated according to the invention to utilize cleaning devices which clean the surfaces of the rollers with a fluid or liquid cleaning detergent.
In certain preferred embodiments of the invention it is provided that the device for conditioning includes apparatus for applying a coating or layer covering the surfaces of the rollers at least in the area of the yarn formation region. These coatings or layers which are applied in the form of fluids or pastes, then determine the friction characteristics. Since these coatings wear out during the spinning operation, they have to be renewed from time to time according to the invention. It can thereby be advantageous to connect the application of such layers with a prior cleaning process at the surfaces of the rollers.
In certain preferred embodiments of the invention it is provided that the device for conditioning includes apparatus for roughening the surfaces of the rollers with closed cover surfaces. With such a roughening the surfaces of the rollers are brought into a desired, predetermined condition affecting the friction characteristics, which condition, especially through wear, will get less effective with a longer operational time period, and therefore has to be renewed at least from time to time according to the invention. It is advantageous according to certain preferred embodiments of the invention to combine this roughening with a prior cleaning and/or a prior application of a coating.
In certain embodiments of the invention it is provided that the device for conditioning includes apparatus for repair works and/or applying of impressions upon the surfaces of the rollers with closed shell surfaces. It is thereby taken into account that the surfaces will change through the wear, dependent upon the operational periods. Here again it is advantageous according to certain embodiments of the invention to also accommodate a combination of a cleaning process and/or application of a coat and/or a roughening process.
In certain embodiments of the invention it is provided that the device for conditioning includes apparatus for polishing the surfaces of the rollers with closed cover surfaces. Also by means of this arrangement, a certain consistent surface quality is obtained through which the friction characteristics are influenced in a predetermined manner. This polishing process may especially be connected with a prior, or also with a subsequent cleaning process according to the invention. It is also contemplated to attend to the polishing process after the application of a layer or coat.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, embodiments in accordance with the present invention.